# US 10,480,811 B1 · Safety gas valve relay driving circuits > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,480,811 B1 - Document ID: US10480811B1 - Status: Granted - Kind: B1 - Application number: 16/218,232 - Filed: 2018-12-12 - Granted: 2019-11-19 - Earliest claimed: 2018-12-12 - Assignees: Emerson Electric Co. - Applicants: Emerson Electric Co. - Inventors: Cuiyun Chen; Yindan Zhang; Yonglong Hu - Web page: https://patentgrep.com/patent/US10480811B1 ## CPC - F24F 11/88: Electrical aspects, e.g. circuits - F24F 11/89: Arrangement or mounting of control or safety devices - H01H 47/001: {Functional circuits, e.g. logic, sequencing, interlocking circuits} - H01H 47/02: for modifying the operation of the relay - H01H 47/22: for supplying energising current for relay coil - H02M 3/07: using capacitors charged and discharged alternately by semiconductor devices with control electrode {, e.g. charge pumps} - F24F 11/32: Responding to malfunctions or emergencies - F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract A safety gas valve relay driving circuit for an HVAC system includes a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay, and a charge pump circuit to control energization of the gas valve relay. The charge pump circuit includes a charge pump capacitor. The driving circuit also includes first and second inputs for receiving first and second driving signals from at least one controller, a low-pass filter coupled between the first input and the charge pump circuit to filter the received first driving signal, and a high-pass filter watchdog circuit coupled between the second input and the charge pump circuit to filter the received second driving signal. Example methods of driving a gas valve relay for an HVAC system are also disclosed. ## Claims ### Claim 1 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; a charge pump circuit coupled with the gas valve relay to control energization of the gas valve relay, the charge pump circuit including a charge pump capacitor; a first input for receiving a first driving signal from at least one controller; a second input for receiving a second driving signal from the at least one controller; a low-pass filter coupled between the first input and the charge pump circuit to filter the received first driving signal; and a high-pass filter watchdog circuit coupled between the second input and the charge pump circuit to filter the received second driving signal; wherein the low-pass filter comprises an RC filter including a resistor coupled between the first input and a capacitor; and wherein the low-pass filter is adapted to inhibit frequencies greater than or equal to twenty kilohertz. ### Claim 2 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; a charge pump circuit coupled with the gas valve relay to control energization of the gas valve relay, the charge pump circuit including a charge pump capacitor; a first input for receiving a first driving signal from at least one controller; a second input for receiving a second driving signal from the at least one controller; a low-pass filter coupled between the first input and the charge pump circuit to filter the received first driving signal; and wherein the high-pass filter watchdog circuit includes a switch, a diode, two capacitors, and two resistors. ### Claim 3 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein the low-pass filter comprises an RC filter including a resistor coupled between the first input and a capacitor. ### Claim 4 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein the high-pass filter watchdog circuit is adapted to inhibit frequencies less than or equal to sixty hertz. ### Claim 5 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein: a first one of the two capacitors and a first one of the two resistors are coupled in parallel between a gate of the switch and an electrical ground; and the diode, the other of the two capacitors and the other of the two resistors are coupled between the second input and the gate of the switch. ### Claim 6 (depends on 5) The safety gas relay driving circuit of claim 5, wherein the first one of the two capacitors is arranged to charge to a level for turning on the switch only when the second driving signal includes a frequency greater than sixty hertz. ### Claim 7 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein the safety gas valve relay driving circuit comprises a single stage furnace control. ### Claim 8 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein the low-pass filter and the high-pass filter watchdog circuit are arranged to inhibit activation of the gas valve relay in response to switching-mode power supply noise and/or alternating-current (AC) line noise. ### Claim 9 (depends on 2) The safety gas valve relay driving circuit of claim 2, wherein the charge pump circuit, the low-pass filter, and the high-pass filter watchdog circuit are arranged to inhibit activation of the gas valve relay in response to failure of one or more components safety gas valve relay driving circuit. ### Claim 10 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; a charge pump circuit coupled with the gas valve relay to control energization of the gas valve relay, the charge pump circuit including a charge pump capacitor; a first input for receiving a first driving signal from at least one controller; a second input for receiving a second driving signal from the at least one controller; a low-pass filter coupled between the first input and the charge pump circuit to filter the received first driving signal; and wherein: the charge pump circuit includes a first switch and a second switch; a base of the first switch is coupled to the low-pass filter; and a base of the second switch is coupled between a collector of the first switch and a voltage bias supply input. ### Claim 11 (depends on 10) The safety gas valve relay driving circuit of claim 10, wherein: the charge pump circuit includes a diode coupled between an emitter of the second switch and the collector of the first switch; and the charge pump capacitor is coupled between the gas valve relay and the emitter of the second switch. ### Claim 12 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; at least one input for receiving a driving signal from at least one controller; a low-pass filter coupled between the at least one input and the gas valve relay to filter the received first driving signal for inhibiting activation of the gas valve relay in response to switched-mode power supply noise; and a high-pass filter coupled between the at least one input and the gas valve relay to filter the received second driving signal for inhibiting activation of the gas valve relay in response to alternating-current (AC) line noise; wherein the low-pass filter is adapted to inhibit frequencies greater than or equal to twenty kilohertz and the high-pass filter is adapted to inhibit frequencies less than or equal to sixty hertz. ### Claim 13 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; at least one input for receiving a driving signal from at least one controller; a low-pass filter coupled between the at least one input and the gas valve relay to filter the received first driving signal for inhibiting activation of the gas valve relay in response to switched-mode power supply noise; and a high-pass filter coupled between the at least one input and the gas valve relay to filter the received second driving signal for inhibiting activation of the gas valve relay in response to alternating-current (AC) line noise; wherein the low-pass filter and the high-pass filter are arranged to inhibit activation of the gas valve relay in response to failure of one or more components safety gas valve relay driving circuit. ### Claim 14 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; at least one input for receiving a driving signal from at least one controller; a low-pass filter coupled between the at least one input and the gas valve relay to filter the received first driving signal for inhibiting activation of the gas valve relay in response to switched-mode power supply noise; and a high-pass filter coupled between the at least one input and the gas valve relay to filter the received second driving signal for inhibiting activation of the gas valve relay in response to alternating-current (AC) line noise; wherein: the low-pass filter comprises an RC filter including a resistor coupled between the first input and a capacitor; and the high-pass filter includes a switch, a diode, two capacitors, and two resistors. ### Claim 15 A safety gas valve relay driving circuit for an HVAC system, the circuit comprising: a gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay; at least one input for receiving a driving signal from at least one controller; a low-pass filter coupled between the at least one input and the gas valve relay to filter the received first driving signal for inhibiting activation of the gas valve relay in response to switched-mode power supply noise; and a high-pass filter coupled between the at least one input and the gas valve relay to filter the received second driving signal for inhibiting activation of the gas valve relay in response to alternating-current (AC) line noise; wherein the safety gas valve relay driving circuit comprises a single stage furnace control. ### Claim 16 A method of driving a gas valve relay for an HVAC system, the gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay, the method comprising: controlling energization of the gas valve relay by a charge pump circuit including a charge pump capacitor; filtering, by a low-pass filter, a first driving signal for controlling energization of the gas valve relay via the charge pump circuit, to inhibit activation of the gas valve relay in response to switched-mode power supply noise; and filtering, by a high-pass filter, the first driving signal or another signal for controlling energization of the gas valve relay via the charge pump circuit, to inhibit activation of the gas valve relay in response to alternating-current (AC) line noise; wherein filtering the first driving signal by the low-pass filter includes inhibiting frequencies greater than or equal to twenty kilohertz, and filtering the first driving signal or another signal by the high-pass filter includes inhibiting frequencies less than or equal to sixty hertz. ### Claim 17 A method of driving a gas valve relay for an HVAC system, the gas valve relay including an output for selectively enabling and disabling a gas valve in an HVAC system according to an energization state of the gas valve relay, the method comprising: controlling energization of the gas valve relay by a charge pump circuit including a charge pump capacitor; filtering, by a low-pass filter, a first driving signal for controlling energization of the gas valve relay via the charge pump circuit, to inhibit activation of the gas valve relay in response to switched-mode power supply noise; filtering, by a high-pass filter, the first driving signal or another signal for controlling energization of the gas valve relay via the charge pump circuit, to inhibit activation of the gas valve relay in response to alternating-current (AC) line noise; inhibiting, by the low-pass filter and the high-pass filter, activation of the gas valve relay in response to failure of one or more components of the low-pass filter, the high-pass filter or the charge pump circuit.